Surface stabilized cathode material for lithium ion batteries and synthesizing method of the same

ABSTRACT

A compound represented by LiaCo(1-x-2y)Mex(M1M2)yOδ, (Formula (I)) wherein Me, is one or more of Li, Mg, Al, Ca, Ti, Zr, V, Cr, Mn, Fe, Ni, Cu, Zn, Ru and Sn, and wherein 0≤x≤0.3, 0&lt;y≤0.4, 0.95≤α≤1.4, and 1.90≤δ≤2.10 is disclosed. Further, particles including such compounds are described.

PRIORITY

This application is a continuation of U.S. patent application Ser. No.15/710,540, now issued U.S. Pat. No. 10,597,307, entitled “SURFACESTABILIZED CATHODE ACTIVE FOR LITHIUM ION BATTERIES AND SYNTHESIZINGMETHOD OF THE SAME,” filed on Sep. 20, 2017, which claims the benefitunder 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No.62/397,725, entitled “High Energy and Stability from Nickel-ManganesePairs in Lithium Cobalt Oxide”, filed on Sep. 21, 2016, U.S. ProvisionalPatent Application No. 62/397,730, entitled “Surface Stabilized CathodeMaterial for Lithium Ion Batteries”, filed on Sep. 21, 2016, and U.S.Provisional Patent Application No. 62/524,864, entitled “SurfaceStabilized Cathode Material for Lithium Ion Batteries and SynthesizingMethod of the Same”, filed on Jun. 26, 2017, each of which isincorporated herein by reference in its entirety.

U.S. GOVERNMENT LICENSE RIGHTS

This invention was made with U.S. government support under WFO ProposalNo. 85F59. This invention was made under a CRADA 1500801 between AppleInc. and Argonne National Laboratory operated for the United StatesDepartment of Energy. The U.S. government has certain rights in theinvention.

FIELD

The described embodiments relate to electrodes for lithium-ion basedbatteries. In particular embodiments, electrode compositions includelithium cobalt oxide containing nickel and manganese pairs, or othermetal pairs, in prescribed proportions for achieving high energycapacity and stable electrodes.

BACKGROUND

Lithium-ion batteries are one of the most popular types of rechargeablebatteries used in a number of consumer electronics. Due to theirrelative high energy density compared to other types of batteries,lithium-ion batteries can be manufactured in small sizes and aretherefore widely the used in portable electronic devices. With theincreasing capabilities of portable electronic devices, more componentsand features are included within the portable electronic devices,thereby leaving less room for batteries. Therefore there is a need forhigher volumetric energy density electrodes, which can be manufacturedin smaller batteries. Furthermore, longer lasting batteries that enduremore reversible charge-discharge cycles are desirable. Thus, there is ademand for high-energy lithium-ion batteries with long-term cyclestabilities.

SUMMARY

This disclosure describes various embodiments that relate to lithiumcobalt oxide compositions having nickel-manganese pairs or otherheterogeneous atomic pairs. The heterogeneous atomic pairs can be metalpairs. The lithium cobalt oxide compositions exhibit high energy andcycle stability.

In a first aspect, a compound is represented by Formula (I):Li_(α)Co_((1-x-2y))Me_(x)(M1M2)_(y)O_(δ)  (Formula (I))

wherein Me selected from one or more of Li, Mg, Al, Ca, Ti, Zr, V, Cr,Mn, Fe, Ni, Cu, Zn, Ru and Sn;

wherein M1 is a metal having a +2 oxidation state;

wherein M2 is a metal having a +4 oxidation state; and

wherein 0≤x≤0.3, 0<y≤0.4, 0.95≤α≤1.4, and 1.90≤δ≤2.10.

According to another aspect, a compound is represented by:Li_(α)Co_((1-2y))(M1M2)_(y)O_(δ)  (Formula (II))

wherein M1 is a metal having a +2 oxidation state;

wherein M2 is a metal having a +4 oxidation state;

wherein M1M2 represents metal pairs; and

wherein 0<y≤0.4, 0.95≤α≤1.4, and 1.90≤δ≤2.10, is described.

According to another aspect, a compound is represented by:Li_(α)Co_(β)M3_(γ)(M4M5)_(ε)O_(δ)  (Formula (III))

wherein M3 is one or more manganese, nickel, aluminum, magnesium,titanium, zirconium, calcium, vanadium, chromium, iron, copper, zinc,ruthenium or a combination thereof;

wherein M4 is a metal having a +2 oxidation state;

wherein M5 is a metal having a +4 oxidation state;

wherein M4M5 represents pairs of M4 and M5; and wherein 0.95≤α≤1.4,0.3≤β≤1.0, 0≤γ≤0.7, 0<ε≤0.4 and 1.90≤δ≤2.10. In some cases, M4 is one ormore of nickel, magnesium, and zinc. In some cases, M5 is one or more ofmanganese, titanium, zirconium, ruthenium, tin, and vanadium.

According to another aspect, a compound is represented by:Li_(α)Co_(β)M4M5)_(ε)O_(δ)  (Formula (IV))

wherein M4 is a metal having a +2 oxidation state;

wherein M5 is a metal having a +4 oxidation state;

wherein M4M5 represents pairs of M4 and M5; and

wherein 0.95≤α≤1.4, 0.3≤β≤1.0, 0<ε≤0.4, and 1.90≤δ≤2.10 is described.

According to an additional aspect, a particle is described.

According to an additional aspect, a particle that includes compounds ina single particle is described. In one aspect, the particle comprisescompounds selected from:a) Li_(a)Co_(b)M6_(c)O_(δ)  Formula (V)

-   -   wherein M6 is one or more of manganese (Mn), nickel (Ni),        aluminum (Al), magnesium (Mg), titanium (Ti), zirconium (Zr),        calcium (Ca), vanadium (V), chromium (Cr), iron (Fe), copper        (Cu), zinc (Zn), and ruthenium (Ru); and wherein 0.90<a≤1.1,        wherein 0.5≤b≤1.0, wherein 0<c≤0.5, and wherein 1.90≤δ≤2.10; and        (b) Li_(a)Co_(β)M3γ(M4M5)_(ε)O_(δ),  Formula (III)

wherein M3 is one or more of manganese, nickel, aluminum, magnesium,titanium, zirconium, calcium, vanadium, chromium, iron, copper, zinc,ruthenium,

wherein M4 is a metal having a +2 oxidation state,

wherein M5 is a metal having a +4 oxidation state,

wherein M4M5 represents pairs of M4 and M5, and

-   -   wherein 0.95≤α≤1.4, 0.3≤β≤1.0, 0≤γ≤0.7, 0<ε≤0.4, and        1.90≤δ≤2.10.

The particle comprising compounds represented by:(a) Li_(α)Co_((1-x-2y))Me_(x)(M1M2)_(y)O_(δ)  Formula (I)

wherein Me is one or more of Li, Mg, Al, Ca, Ti, Zr, V, Cr, Mn, Fe, Ni,Cu, Zn, Ru and Sn,

wherein M1 is a metal having a +2 oxidation state;

wherein M2 is a metal having a +4 oxidation state;

wherein M1M2 represents metal pairs; and

wherein 0≤x≤0.3, 0<y≤0.4, 0.95≤α≤1.4, and 1.90≤δ≤2.10; and(b) Li_(α)Co_(β)M3_(γ)(M4M5)_(ε)O_(δ),  Formula (III)

wherein M3 is one or more of manganese, nickel, aluminum, magnesium,titanium, zirconium, calcium, vanadium, chromium, iron, copper, zinc,ruthenium,

wherein M4 is a metal having a +2 oxidation state,

wherein M5 is a metal having a +4 oxidation state,

wherein M4M5 represents pairs of M4 and M5, and

wherein 0.95≤α≤1.4, 0.3≤β≤1.0, 0≤γ≤0.7, 0<ε≤0.4, and 1.90≤δ≤2.10.

Alternatively, the particle can include compounds represented by Formula(II) and/or Formula (IV), as described herein. In various aspects, thecompounds of Formula (I) and Formula (III) can be different.

The particle includes a core and a coating disposed on the core. Thecore can be any cathode active material known in the art. In somevariations, the core can be a compound of Formula (V), Formula (I), orFormula (II). Further, the coating can be a compound of Formula (III) orFormula (IV).

According to another embodiment, a cathode for a lithium-ion battery isdescribed. The cathode includes a composition, or combination ofcompositions, described above.

According to a further embodiment, a method of synthesizing alithium-oxide cathode active material for a lithium-ion battery isdescribed. The method includes reacting a metal solution with a chelateagent and a base solution at an alkaline pH to form a particulatesolution through a coprecipitation process; washing, filtering anddrying the particulate solution to collect hydroxide precursorparticles; blending the collected particles with a lithium salt; andreacting the blended particles at a first elevated temperature toproduce base particles.

These and other aspects of the disclosure will be described in detailbelow and it is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of thedisclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements.

FIG. 1 shows a crystal structure model of a cobalt oxide portion of alithium cobalt oxide composition, according to an illustrativeembodiment;

FIG. 2 shows a graph illustrating a relationship between the number andtype of metal pairs within a lithium cobalt oxide material and relativetotal energy, according to an illustrative embodiment;

FIG. 3 shows a graph illustrating relative energy of battery cells as afunction of number of atomic pairs, according to an illustrativeembodiment;

FIGS. 4 and 5 show scanning electron microscope (SEM) images of alithium cobalt oxide composition with nickel-manganese pairs at higherand lower magnifications, respectively according to an illustrativeembodiment;

FIG. 6 shows MAS NMR spectra for lithium cobalt oxide compositionshaving nickel-manganese pairs, according to an illustrative embodiment;

FIG. 7 shows a differential capacity analysis plot for a battery cellhaving a cathode with a lithium cobalt oxide composition withnickel-manganese pairs according to an illustrative embodiment;

FIG. 8 shows Raman spectra of lithium cobalt oxide compositions havingnickel-manganese pairs and lithium cobalt oxide compositions withoutnickel-manganese pairs.

FIG. 9 shows a heat flow versus temperature graph comparing thermalstability of different cathode materials, according to an illustrativeembodiment;

FIG. 10 shows a flowchart indicating a method of forming a battery cellwith an electrode with a lithium cobalt oxide composition havingnickel-manganese pairs, according to an illustrative embodiment;

FIGS. 11A-11D show coated particles for cathode materials in accordancewith some embodiments.

FIGS. 12A and 12B show SEM images of uncoated and coated particleshaving various lithium cobalt oxide compositions, according to anillustrative embodiment;

FIG. 13 shows Raman spectra of particles coated and uncoated coated withvarious lithium cobalt oxide compositions, according to an illustrativeembodiment;

FIG. 14 shows a graph illustrating energy retention of battery cellshaving various lithium cobalt oxide compositions, according to anillustrative embodiment;

FIG. 15 shows a graph illustrating energy retention of battery cellshaving particles of different coating compositions after a number ofcharge and discharge cycles, according to an illustrative embodiment;

FIG. 16 shows a graph illustrating energy retention of half cells havingparticles of different compositions after a number of charge anddischarge cycles, according to an illustrative embodiment;

FIGS. 17A-17E show capacity analysis plots for battery cells havingvarious lithium cobalt oxide compositions, according to an illustrativeembodiment;

FIG. 18 shows an electronic device having a battery, according to anillustrative embodiment;

FIGS. 19A-19C show X-ray diffraction patterns of various lithium cobaltoxide compositions, according to an illustrative embodiment;

FIG. 20 shows a graph illustrating energy retention of cells havingparticles of different compositions at a higher temperature, accordingto an illustrative embodiment;

FIG. 21 shows an SEM image of spherical transition metal hydroxideparticles prepared by a coprecipitation process, according to anillustrative embodiment;

FIG. 22 shows an SEM image of a coprecipitated precursor that has beenground to sub-micron size, according to an illustrative embodiment;

FIG. 23 shows an SEM image of calcined particles in accordance with thedisclosure.

FIG. 24 is SEM images showing an effect of calcination temperature onthe extent of reaction of the overlay with the base particle, accordingto an illustrative embodiment;

FIG. 25 is a process of flow chart showing an alternative method ofoverlay using metal ion solution, according to an illustrativeembodiment;

FIG. 26 is a graph showing discharge capacity v. cycling demonstratingimproved capacity retention overlay by overlaying NM1616, according toan illustrative embodiment;

FIG. 27 is a graph of normalized energy retention illustrating theimproved retention of overlaid materials, according to an illustrativeembodiment;

FIG. 28 is a graph showing the average voltage with cycling improvedwith ab increase of MN161 content, according to an illustrativeembodiment;

FIG. 29 is a Raman microspectroscopy spectra showing that the overlaysurface is similar to bulk NM1616, according to an illustrativeembodiment;

FIG. 30 is a differential scanning calorimetry showing better thermalstability with NM1616 overlay, according to an illustrative embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

Lithium cobalt oxide compositions suitable for use in lithium-ionbattery cells are described. In some embodiments, the lithium cobaltoxide compositions are doped with pairs of metals. The first metal has a+2 oxidation state (e.g., Ni), and the second metal has a +4 oxidationstate (e.g., Mn). The first and second metals form pairs within a basecobalt oxide lattice structure. Without being limited to a particularmechanism or mode of action, the pairs can form a lower energy and morestable lattice configuration. In this way, the metal pairs (e.g., Ni—Mnpairs) can provide lithium-ion electrodes that are less susceptible tostructural degradation after numerous charge and discharge cyclescompared to lithium cobalt oxide compositions without metal pairs. Themetal pairs are also associated with a stable cathode interface withelectrolyte, thereby providing better surface stability at high chargevoltage compared to battery cells with lithium cobalt oxide electrodecompositions without metal pairs. In some embodiments, the lithiumcobalt oxide compositions include heterogeneous atomic pairs other thannickel and manganese, and that can also be associated with high energycapacity battery cells.

Lithium cobalt oxide compositions described herein can be characterizedby any suitable technique, including Raman spectroscopy, and nuclearmagnetic resonance (NMR). Charge and discharge cycling of a battery cellhaving lithium cobalt oxide compositions with metal pairs indicate abetter capacity retention over numerous cycles compared to a batterycell having the lithium cobalt oxide compositions without metal pairs.

In some embodiments, lithium cobalt oxide compositions havingheterogeneous atomic pairs are in the form of a coating that covers acore particle material. The core can be composed of a lithium cobaltoxide composition without heterogeneous atomic pairs, or can be composedof other suitable cathode material. The combination of core and coatingmaterials can provide a surface-stable high energy cathode.

In other embodiments, the particle can be a combination of compounds(e.g., by a sintered core and coating). A first compound can be composedof any suitable material for a cathode active material known in the art.The first compound can be composed of a lithium cobalt oxide compositionwithout heterogeneous atomic pairs, or can be composed of other suitablecathode material. In some embodiments, the first compound can berepresented by the formula LiTM_(1-x)Me_(x)O₂ wherein TM is Co, Mn orNi; Me is Li, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru. In otherembodiments, the first compound can be represented by the formulaLiMn_(2-x)Me_(x)O₄, wherein Me is Li, Ni, Co, Mg, Al, Ti, Zr, Ca, V, Cr,Fe, Cu, Zn or Ru. In further embodiments, the first compound can berepresented by the formula LiTM_(1-x)Me_(x)PO₄, wherein TM is Co, Mn, Nior Fe; Me is Li, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru. Inadditional embodiments, the first compound can be represented by theformula Li₂MO₃*LiTM_(1-x)Me_(x)O₂, wherein M is Mn, Ru, Ti or Zr, TM isCo, Mn or Ni, Me is Li, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru. Instill further, first compound can be a compound of Formula (I) orFormula (II), as described herein. The second compound can be a compoundof Formula (III) or Formula (IV), as described herein. The combinationof the two materials in the particles can provide a surface-stable highenergy cathode.

The particles can also be coated with a dielectric material to protectthe lithium cobalt oxide material from chemical agents within thebattery electrolyte that can degrade the lithium cobalt oxide material.

The lithium cobalt oxide compositions described herein are well suitedfor use in electrodes of lithium-ion batteries for any of a number ofsuitable consumer electronic products. For example, the lithium cobaltoxide compositions described herein can be used in batteries forcomputers, portable electronic devices, wearable electronic devices, andelectronic device accessories, such as those manufactured by Apple Inc.,based in Cupertino, Calif.

These and other embodiments are discussed below with reference to FIGS.1-30. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these Figures is forexplanatory purposes only and should not be construed as limiting.

Materials described herein are based on lithium cobalt oxidecompositions and are suitable for application in positive electrodes oflithium-ion based batteries. In some embodiments, the lithium cobaltoxide compositions can be represented by:Li_(α)Co_((1-x-2y))Me_(x)(M1M2)_(y)O_(δ)  (Formula (I))

where Me is one or more of lithium (Li), magnesium (Mg), aluminum (Al),calcium (Ca), titanium (Ti), zirconia (Zr), vanadium (V), chromium (Cr),manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn),ruthenium (Ru) and tin (Sn); and where 0≤x≤0.3, 0≤y≤0.4, 0.95≤α≤1.4, and1.90≤δ≤2.10. Note that Me can be a single element or combination ofelements. In some cases, Me includes a suitable transition metal. M1M2represents pairs of M1 and M2. In some cases, M1 is nickel and M2 ismanganese.

In the case where x is zero, the lithium cobalt oxide composition can berepresented by:Li_(α)Co_((1-2y))(M1M2)_(y)O_(δ)  (Formula (II))wherein M1 and M2 are described as above.

The lithium cobalt oxide compositions in accordance with Formulae (I)and (II) can be used as positive electrodes (cathodes) withinlithium-ion battery cells. The lithium cobalt oxide compositions includethe substitution of some cobalt (Co) with a pair of first and secondmetals (which can be referred to as “metal pairs”). The first metal hasa +2 oxidation state, and the second metal has a +4 oxidation state. Thefirst metal can be nickel, and the second metal can be manganese, whichform nickel-manganese pairs (which can be referred to as “Ni—Mn pairs”).Metal pairs (e.g., Ni—Mn pairs) are short-range pairing of the first andsecond metal within the crystal structure of the lithium cobalt oxidecompositions. Without wishing to be limited to a particular embodimentor mode of action, the metal pairs are associated with more stable oxidecompositions compared to oxide compositions without the metal pairs,thereby providing a more robust framework for Li intercalation anddeintercalation and better cycle life lithium-ion battery cells, whichwill be described below in detail.

In some embodiments, the lithium cobalt oxide compositions includeatomic pairs of metals other than nickel and manganese. For example, insome embodiments, one of the atomic pairs is a transition metal having a+4 oxidation state and the other is an element having a +2 oxidationstate. These atomic pairs include different elements, and thus can bereferred to as heterogeneous atomic pairs. For instance, in addition toor instead of Ni—Mn pairs, the lithium cobalt oxide compositions caninclude one or more of nickel and titanium (Ni—Ti) pairs, magnesium andtitanium (Mg—Ti) pairs, magnesium and manganese (Mg—Mn) pairs, nickeland zirconium (Ni—Zr) pairs, magnesium and zirconium (Mg—Zr) pairs, etc.In some embodiments, the lithium cobalt oxide compositions include morethan one type of atomic metal pairs. For example, a lithium cobalt oxidecomposition can include Ni—Mn pairs as well as one or more of Ni—Tipairs, Mg—Mn pairs, Mg—Ti pairs, Ni—Zr pairs, Mg—Zr pairs, Ni—V pairs,Mg—V pairs, etc. That is, the lithium cobalt oxide compositions caninclude any suitable combination of +4 transition metal-containingpairs.

In some embodiments, x is 0. In some embodiments of Formula (I),0<x≤0.3. In some embodiments of Formula (I), x is greater than or equalto 0.1. In some embodiments of Formula (I), x is greater than or equalto 0.2. In some embodiments of Formula (I), x is less than or equal to0.3. In some embodiments of Formula (I), x is less than or equal to 0.2.

In some embodiments of Formula (I), y is greater than or equal to 0.1.In some embodiments of Formula (I), y is greater than or equal to 0.2.In some embodiments of Formula (I), y is greater than or equal to 0.3.In some embodiments of Formula (I), y is less than or equal to 0.4. Insome embodiments of Formula (I), y is less than or equal to 0.3. In someembodiments of Formula (I), y is less than or equal to 0.2. In someembodiments of Formula (I), y is less than or equal to 0.1. In someembodiments, 0.20≤y≤0.25. In some embodiments, 0.02≤y≤0.06. In someembodiments, 0.05≤y≤0.09. In some embodiments, 0.08≤y≤0.12. In someembodiments, 0.14≤y≤0.18. In some embodiment, 0.20≤y≤0.25.

In some embodiments of Formula (I), α is greater than or equal to 0.95.In some embodiments of Formula (I), α is greater than or equal to 0.98.In some embodiments of Formula (I), α is greater than or equal to 1.0.In some embodiments of Formula (I), α is greater than or equal to 1.1.In some embodiments of Formula (I), α is greater than or equal to 1.2.In some embodiments of Formula (I), α is less than or equal to 1.4. Insome embodiments of Formula (I), α is less than or equal to 1.3. In someembodiments of Formula (I), α is less than or equal to 1.2. In someembodiments of Formula (I), α is less than or equal to 1.1. In someembodiments of Formula (I), α is less than or equal to 1.2. In someembodiments of Formula (I), α is less than or equal to 1.1. In someembodiments of Formula (I), α is less than or equal to 1.0. In someembodiments of Formula (I), α is less than or equal to 0.99. In someembodiments of Formula (I), α is less than or equal to 0.98. In someembodiments of Formula (I), α is less than or equal to 0.97. In someembodiments of Formula (I), α is less than or equal to 0.96.

It will be understood that substituent quantities can be in anycombination, as described herein.

In some embodiments, the lithium cobalt oxide compositions can berepresented by:Li_(α)Co_(β)M3γ(M4M5)_(ε)O_(δ)  (Formula (III))where M3 is one or more of manganese (Mn), nickel (Ni), aluminum (Al),magnesium (Mg), titanium (Ti), zirconium (Zr), calcium (Ca), vanadium(V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), and ruthenium(Ru); where M4 is a metal having a +2 oxidation state; where M5 is ametal having a +4 oxidation state; and where 0.9≤α≤1.4, 0.3≤β≤1.0,0≤γ≤0.7, 0<ε≤0.4, and 1.90≤δ≤2.10.

In particular embodiments, M4 is one or more of nickel (Ni), magnesium(Mg), and zinc (Zn); and M5 is one or more of manganese (Mn), titanium(Ti), zirconium (Zr), and vanadium (V).

In some embodiments, γ is 0. In some embodiments of Formula (III),0<γ≤0.3. In some embodiments of Formula (III), γ is greater than orequal to 0.1. In some embodiments of Formula (III), γ is greater than orequal to 0.2. In some embodiments of Formula (III), γ is less than orequal to 0.3. In some embodiments of Formula (III), γ is less than orequal to 0.2.

In some embodiments of Formula (III), ε is greater than or equal to 0.1.In some embodiments of Formula (III), ε is greater than or equal to 0.2.In some embodiments of Formula (III), ε is greater than or equal to 0.3.In some embodiments of Formula (III), ε is less than or equal to 0.4. Insome embodiments of Formula (III), ε is less than or equal to 0.3. Insome embodiments of Formula (III), ε is less than or equal to 0.2. Insome embodiments of Formula (III), ε is less than or equal to 0.1. Insome embodiments, 0.20≤ε≤0.25. In some embodiments, 0.02≤ε≤0.06. In someembodiments, 0.05≤ε≤0.09. In some embodiments, 0.08≤ε≤0.12. In someembodiments, 0.14≤ε≤0.18. In some embodiment, 0.20≤ε≤0.25.

In some embodiments of Formula (III), α is greater than or equal to0.95. In some embodiments of Formula (III), α is greater than or equalto 0.98. In some embodiments of Formula (III), α is greater than orequal to 1.0. In some embodiments of Formula (III), α is greater than orequal to 1.1. In some embodiments of Formula (III), α is greater than orequal to 1.2. In some embodiments of Formula (III), α is less than orequal to 1.4. In some embodiments of Formula (III), α is less than orequal to 1.3. In some embodiments of Formula (III), α is less than orequal to 1.2. In some embodiments of Formula (III), α is less than orequal to 1.1. In some embodiments of Formula (III), α is less than orequal to 1.2. In some embodiments of Formula (III), α is less than orequal to 1.1. In some embodiments of Formula (III), α is less than orequal to 1.0. In some embodiments of Formula (III), α is less than orequal to 0.99. In some embodiments of Formula (III), α is less than orequal to 0.98. In some embodiments of Formula (III), α is less than orequal to 0.97. In some embodiments of Formula (III), α is less than orequal to 0.96.

In some embodiments of Formula (III), β is greater than or equal to 0.3.In some embodiments of Formula (III), β is greater than or equal to 0.5.In some embodiments of Formula (III), β is greater than or equal to 0.7.In some embodiments of Formula (III), β is greater than or equal to 0.9.In some embodiments of Formula (III), β is less than or equal to 1.0. Insome embodiments of Formula (III), β is less than or equal to 0.8. Insome embodiments of Formula (III), β is less than or equal to 0.6. Insome embodiments of Formula (III), β is less than or equal to 0.4.

It will be understood that any substituent quantities in any Formula canbe in any combination, as described herein.

In another embodiment, the lithium cobalt oxide particles can include acombination of compounds of Formula (V) and Formula (III) as follows:(a) Li_(a)Co_(b)M6_(c)O_(δ)  (Formula (V))where M6 is one or more of manganese (Mn), nickel (Ni), aluminum (Al),magnesium (Mg), titanium (Ti), zirconium (Zr), calcium (Ca), vanadium(V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), and ruthenium(Ru); and where 0.90≤a≤1.1, 0.5≤b≤1.0, 0<c≤0.5, 1.90≤δ≤2.10; and(b) Li_(α)Co_(β)M3γ(M4M5)_(ε)O_(δ)  (Formula (III))wherein M3 is one or more of manganese, nickel, aluminum, magnesium,titanium, zirconium, calcium, vanadium, chromium, iron, copper, zinc,ruthenium,wherein M4 is a metal having a +2 oxidation state,wherein M5 is a metal having a +4 oxidation state,wherein M4M5 represents pairs of M4 and M5, andwherein 0.95≤α≤1.4, 0.3≤β≤1.0, 0≤γ≤0.7, 0<ε≤0.4, and 1.90≤δ≤2.10.

In some instances, M6 can be the combination of i) Mn, Ni, or thecombination of Mn and Ni, and ii) Al as a dopant.

In some embodiments, Formula (V) is a layered hexagonal rock-saltstructure represented as LiTM₁-xMexM7O₂; where TM is Co, Mn or Ni; Me isLi, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru. In some cases, the corehas a spinel cubic structure represented as LiMn₂-xMexO₄; where Me isLi, Ni, Co, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru. In someembodiments, the core has an olivine structure represented asLiTM₁-xMexPO₄; where TM is Co, Mn, Ni or Fe; Me is Li, Mg, Al, Ti, Zr,Ca, V, Cr, Fe, Cu, Zn or Ru. In some embodiments, the core is alayered-layered material such as represented by Li₂MO₃*LiTM1-xMexO₂;where M is Mn, Ru, Ti or Zr; TM is Co, Mn or Ni; Me is Li, Mg, Al, Ti,Zr, Ca, V, Cr, Fe, Cu, Zn or Ru.

A concentration of compound (b) Li_(α)Co_(β)(M4M5)_(ε)O_(δ) can begradually increased or decreased in the compound (a)Li_(a)Co_(b)M6_(c)O_(δ) Formula (V) from a localized position tosurrounding directions. Further, the composition may include adielectric coating on the compound (b)Li_(α)Co_(β)M1_(γ)(M4M5)_(ε)O_(δ).

In another embodiment, the lithium cobalt oxide particles can include acombination of compounds of Formula (I) and Formula (III) as follows:(a) Li_(α)Co_((1-x-2y))Me_(x)(M1M2)_(y)O_(δ)  (Formula (I))wherein Me is one or more of Li, Mg, Al, Ca, Ti, Zr, V, Cr, Mn, Fe, Ni,Cu, Zn, Ru and Sn, and wherein 0≤x≤0.3, 0<y≤0.4, 0.95≤α≤1.4, and1.90≤δ≤2.10; and(b) Li_(α)Co_(β)M3_(γ)(M4M5)_(ε)O_(δ)  (Formula (III))wherein M3 is one or more of manganese, nickel, aluminum, magnesium,titanium, zirconium, calcium, vanadium, chromium, iron, copper, zinc,ruthenium,wherein M4 is a metal having a +2 oxidation state,wherein M5 is a metal having a +4 oxidation state,wherein M4M5 represents pairs of M4 and M5, andwherein 0.95≤a≤1.4, 0.3≤β≤1.0, 0≤γ≤0.7, 0≤ε≤0.4, and 1.90≤δ≤2.10.

M1M2 represents pairs of M1 and M2. M1 can be nickel and M2 can bemanganese. M1 can be one or more of nickel, magnesium, and zinc. M2 canbe one or more of manganese, titanium, zirconium, and vanadium. Theparticle has an energy density higher at an interior of the particlethan at a surface of the particle and has energy retentive propertieshigher at a surface of the particle than at an interior of the particle.

A concentration of compound (b) Li_(α)Co_(β)M1_(γ)(M4M5)_(ε)O_(δ) can begradually increased or decreased in the compound (a)Li_(α)Co_((1-x-2y))Me_(x)(M1M2)_(y)O_(δ) from a localized position tosurrounding directions. Also, the composition may include a dielectriccoating on the compound (b) Li_(α)Co_(β)M1_(γ)(M4M5)_(ε)O_(δ).

In another embodiment, the lithium cobalt oxide compositions can berepresented by a combination of Formula (II) and Formula (IV) asfollows:(a) Li_(α)Co_((1-2y))(M1M2)_(y)O_(δ)  (Formula (II))wherein 0<y≤0.4, 0.95≤α≤1.4, 1.90≤δ≤2.10, and wherein M1M2 representsnickel-manganese pairs; and(b) Li_(α)Co_(β)(M4M5)_(ε)O_(δ)  (Formula (IV))wherein M4 is a metal having a +2 oxidation state,wherein M5 is a metal having a +4 oxidation state,wherein M4M5 represents pairs of M3 and M4, andwherein 0.95≤α≤1.4, 0.3≤β≤1.0, 0<ε≤0.4 and 1.90≤δ≤2.10.

In some variations, M4 can be one or more of nickel, magnesium, andzinc. In some variations, M5 can be one or more of manganese, titanium,zirconium, and vanadium. The particle including the compounds of Formula(I) and Formula (III) can have an energy density higher at an interiorof the particle than at a surface of the particle and has energyretentive properties higher at a surface of the particle than at aninterior of the particle. A concentration of compound (b)Li_(α)Co_(β)M1_(γ)(M4M5)_(ε)O_(δ) (Formula (III)) can be graduallyincreased or decreased in the compound (a)Li_(α)Co_((1-x-2y))Me_(x)(M1M2)_(y)O_(δ) (Formula (I)) from a localizedposition to surrounding directions. Also, a dielectric coating may bedisposed on the particle.

In other variations, this Formula (V) can be represented as representedby Formula (VIa) or Formula (VIb).

Formula (VIa) is represented by the following formula:(v)[M⁷O₂].(1-v)[Co_(1-σ)M⁸O₂]  (Formula VIa)wherein M⁷ is one or more elements with an average oxidation state of4+(i.e., tetravalent); M⁸ is one or more monovalent, divalent,trivalent, and tetravalent elements; 0.01≤v<1.00, and 0≤σ≤0.05. In somevariations, M⁷ is selected from Mn, Ti, Zr, Ru, and a combinationthereof. In some variations, M⁸ is selected from B, Na, Mg, Ti, Ca, V,Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo and a combinationthereof. In some variations, M⁷ is Mn. In some variations, M⁸ is Al.

In some embodiments, 0.01≤v≤0.50. In some embodiments, 0.01≤v≤0.50. Insome embodiments, 0.01≤v≤0.30. In some embodiments, 0.01≤v<0.10. In someembodiments, 0.01≤v<0.05. In some variations, 0<σ≤0.05. In somevariations, 0<σ≤0.03. In some variations, 0<σ≤0.02. In some variations,0<σ≤0.01. In some variations, 0.01≤v<0.05, and 0<σ≤0.05.

In some variations, Al is at least 500 ppm. In some variations, Al is atleast 750 ppm. In some variations, Al is at least 900 ppm. In somevariations, Al is less than or equal to 2000 ppm. In some variations, Alis less than or equal to 1500 ppm. In some variations, Al is less thanor equal to 1250 ppm. In some variations, Al is less than or equal to1000 ppm. In some variations, Al is less than or equal to 900 ppm. Insome variations, Al is less than or equal to 800 ppm. In somevariations, Al is less than or equal to 700 ppm. In some variations, Alis less than or equal to 600 ppm. In some instances, when M⁸ (e.g., Al)is expressed in ppm, in optional variations, the compound can berepresented as (v)[Li₂M⁷O₃].(1-v)[Li_(α)Co_(w)O₂] and the amount of M⁸can be represented as M⁸ in at least a quantity in ppm, as otherwisedescribed above. In some embodiments, 0.5≤w≤1. In some embodiments,0.8≤w≤1. In some embodiments, 0.96≤w≤1. In some embodiments, 0.99≤w≤1.In some embodiments, w is 1.

Formula (VIb) is represented by the following formula:(v)[Li₂M⁷O₃].(1-v)[Li_(α)Co_(1-σ)M⁸ _(σ)O₂]  (Formula VIb)wherein M⁷ is one or more elements with an average oxidation state of4+(i.e., tetravalent); M⁸ is one or more monovalent, divalent,trivalent, and tetravalent elements; 0.95≤α≤0.99; 0.01≤v<1.00, and0.5≤w≤1, and 0≤σ≤0.05. In some variations, M⁷ is selected from Mn, Ti,Zr, Ru, and a combination thereof. In some variations, M⁸ is selectedfrom B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga,Zr, Ru, Mo and a combination thereof. In some variations, M⁷ is Mn. Insome variations, M⁸ is Al.

In some embodiments, 0.01≤v≤0.50. In some embodiments, 0.01≤v<0.50. Insome embodiments, 0.01≤v≤0.30. In some embodiments, 0.01≤v<0.10. In someembodiments, 0.01≤v<0.05. In some variations, 0<σ≤0.05. In somevariations, 0<σ≤0.03. In some variations, 0<σ≤0.02. In some variations,0<σ≤0.01. In some variations, 0.95≤σ<0.99, 0.01≤v<0.05, 0.96≤w<1, and0<σ≤0.05.

In some variations, M⁸ (e.g., Al) is at least 500 ppm. In somevariations, M⁸ (e.g., Al) is at least 750 ppm. In some variations, M⁸(e.g., Al) is at least 900 ppm. In some variations, M⁸ (e.g., Al) isless than or equal to 2000 ppm. In some variations, M⁸ (e.g., Al) isless than or equal to 1500 ppm. In some variations, M⁸ (e.g., Al) isless than or equal to 1250 ppm. In some variations, M⁸ (e.g., Al) isless than or equal to 1000 ppm. In some variations, M⁸ (e.g., Al) isless than or equal to 900 ppm. In some variations, M⁸ (e.g., Al) is lessthan or equal to 800 ppm. In some variations, M⁸ (e.g., Al) is less thanor equal to 700 ppm. In some variations, M⁸ (e.g., Al) is less than orequal to 600 ppm. In some instances, when M⁸ (e.g., Al) is expressed inppm, the compound can be represented as(v)[Li₂M⁷O₃].(1-v)[Li_(α)Co_(w)O₂] and the amount of M⁸ can berepresented as M⁸ in at least a quantity in ppm, as otherwise describedabove. In some variations, 0.5≤w≤1. In some variations, 0.8≤w≤1. In somevariations, 0.96≤w≤1. In some variations, 0.99≤w≤1. In some variations,w is 1.

It will be understood that the substituents in Formulae (II) can be inany variation as described for Formula (I), and the substituents forFormula (IV) can be in any variation as described for Formula (III).

In some embodiments, the compositions in accordance with Formulae I-IVare cobalt-rich, meaning that the atomic percentage of cobalt is largerthan the atomic percentages of the first and second metal. It should benoted, however, that the embodiments described herein are not limited tocobalt-rich compositions. As indicated by Formulae I and II, the amountof metal pairs within the lithium cobalt oxide compositions can vary inaccordance with y—which can be associated with variables x, α and δ.

In addition to the metal pairs (e.g., Ni—Mn pairs), the lithium contentwithin the lithium cobalt oxide compositions can be controlled. In someembodiments, α is less than 1—in which case the lithium cobalt oxidecomposition can be referred to as lithium-deficient since thecomposition has relatively less lithium than cobalt and Me and/or metalpairs. That is, the lithium cobalt oxide composition has less than thenominal stoichiometric amount of lithium. In other embodiments, a isgreater than 1—in which case the lithium cobalt oxide composition can bereferred to as lithium-rich since the composition has relatively morelithium than cobalt and Me and/or metal pairs. That is, the lithiumcobalt oxide composition has greater than the nominal stoichiometricamount of lithium.

With regard to oxygen, in accordance with Formulae (I)—(V), the amountof oxygen can be greater or less than a nominal stoichiometric amount ofoxygen. That is, in some embodiments, δ is greater or less than two.This variance of δ from 2 can compensate for a charge deficiency withinthe lithium cobalt oxide composition due to variations in one or more ofthe other elements: x, y and α, in Formula (I), y and α in Formula (II),α, β, γ, and ε in Formula (III), and α, β, and ε in Formula (IV). Inparticular, δ can be greater or less than 2 in order to create acharge-neutral lithium cobalt oxide composition.

Stable atomic configurations of lithium cobalt oxide compositions inaccordance with Formulae (I) or (II) can be calculated using, forexample, density functional theory (DFT) calculations. Table 1 belowshows DFT energy calculations performed on several atomic configurationshaving about 4 atomic % nickel and about 4 atomic % manganese (referredto herein as “NM44”). Table 1 shows calculated energy, relative energy,relative energy per formula unit, and probabilities of Ni—Mn pairs,Mn—Mn pairs, and Ni—Ni pairs for 15 different configurations.

TABLE 1 Relative E (meV)/ Relative E formula Ni—Mn Mn—Mn Ni—NiConfiguration E (eV) (eV) unit pairs pairs pairs c1 −1791.3512 0.5572537.7 6 3 3 c2 −1791.7716 0.136899 1.9 8 2 2 c3 −1790.8628 1.045661 14.5 43 3 c4 −1791.1392 0.769254 10.7 4 3 3 c5c −1791.2836 0.624940 8.7 6 3 1c6 −1791.6337 0.274809 3.8 6 1 3 c7 −1791.8346 0.073948 1.0 7 0 0 c8−1791.7485 0.160006 2.2 6 0 0 c9 −1791.8638 0.044662 0.6 7 0 0 c10−1791.7407 0.167785 2.3 7 1 1 c11 −1791.9085 0.000000 0.0 8 1 0 c12−1791.1349 0.773651 10.7 c13 −1791.2917 0.616757 8.6 4 1 1 c14−1791.1372 0.771294 10.7 c5 −1791.1107 0.797835 11.1 4 1 1

Table 1 indicates that of the several possible structural modelconfigurations considered, c11 shows the lowest relative energy with 8Ni—Mn pairs, 1 Mn—Mn pair and 0 Ni—Ni pairs. The second and third lowestrelative energy configurations are c7 and c9, both of which have 7 Ni—Mnpairs, 0 Mn—Mn pairs and 0 Ni—Ni pairs. This indicates that theconfigurations having the most Ni—Mn pairs relative to Mn—Mn pairs and 0Ni—Ni pairs can be associated with a low energy configuration—that is,are calculated to be the most stable.

FIG. 1 illustrates a crystal structure model of the configuration c11.The crystal structure model in FIG. 1 shows nickel, manganese, cobalt,Me and oxygen atoms arranged in a trigonal crystal structure (R-3m),sometimes referred to as a rhombohedral lattice structure. It should benoted that FIG. 1 shows a crystal structure model of a cobalt oxideportion of the lithium cobalt oxide composition and lithium is not shownsince lithium ions are transported between the cathode and anode of thelithium-ion battery cell. In particular, the cathode material iscomposed of layers of cobalt oxide structure doped with nickel andmanganese (and in some cases Me), with layers of mobile lithium inbetween the doped cobalt oxide layers. During discharging, lithium ionsin the battery cell move from the cathode via an electrolyte to theanode, thereby allowing electrons to flow as electric current. Duringcharging, the lithium ions move from the anode via the electrolyte tothe cathode.

FIG. 1 illustrates that when nickel and manganese are added to cobaltoxide layers, the nickel and manganese form a short-range orderdistribution. For example, the Ni and Mn atoms can be attracted to eachother and form a chemical bond, thereby resulting in NiMn pairs withinthe LiCoO₂ crystal structure. That is, nickel and manganese are notrandomly distributed within the crystal structure, but rather ordered inNi—Mn pairs. In particular, the Ni—Mn pairs are predicted to residewithin a sub-lattice of the LiCoO₂ crystal structure, as shown inFIG. 1. It is believed that these Ni—Mn pairs provide a short-rangeorder that results in a lower energy and more stable structure comparedto a LiCoO₂ structure without Ni—Mn pairs.

FIG. 2 shows a graph illustrating a relationship between the number andtype of metal pairs within a lithium cobalt oxide material and relativetotal energy (meV/f.u.), as calculated using DFT. The DFT calculationsare based on the number of Ni—Mn pairs, Mn—Mn pairs and Ni—Ni pairswithin a lithium cobalt oxide lattice structure. These calculatedresults indicate that the greater amounts of Ni—Mn pairs in lithiumcobalt oxide compositions, the lower relative total energies, andtherefore more stable the material than lithium cobalt oxidecompositions with lesser amounts of Ni—Mn pairs and having Mn—Mn pairsand Ni—Ni pairs. Thus, the lithium cobalt oxide compositions havingmetal pairs containing one atom in a +4 oxidation state (Mn) and theother atom in a +2 oxidation state (Ni) are calculated to provide a morestable lithium cobalt oxide composition than those having pairs of thesame type of atoms.

Embodiments described herein are not limited to NM44 compositions. Forexample, “NM77” (having about 7 atomic % nickel and about 7 atomic %manganese), “NM1010” (having about 10 atomic % nickel and about 10atomic % manganese), and “NM1616” (having about 16 atomic % nickel andabout 16 atomic % manganese) also show evidence of short-range orderingdue to Ni—Mn pairs. In fact, any suitable compositions in accordancewith the Formulae described herein may have short-range ordering due toNiMn pairs. The Ni—Mn pairs within the LiCoO₂ structure can becharacterized by Raman spectroscopy and nuclear magnetic resonancespectroscopy (NMR). Described below are some data using these and othercharacterization techniques.

Table 2 below shows MAS NMR peak assignments for the NM1616 samples ofFIG. 3. The peak assignments marked in bold can be consideredfingerprints for Ni—Mn short-range order interaction.

TABLE 2 Measured NMR (calculated Spectra Shift shift for (ppm) PossibleAssignments configuration) −23 1Ni^(st) −15 −47 1Mn^(nd) −60 −811Ni^(st) 1Mn^(nd) −75 −98 2Ni^(st) 1Mn^(nd) −90 −136 1Ni^(st) 2Mn^(nd)−135 4.8 2Mn^(st) 4Ni^(st) 3Mn^(nd) 4 55 1Ni^(nd) 2Ni^(st) 1Mn^(nd) 5088 1Ni^(nd) 1Mn^(nd) 84 125 1Ni^(nd) or 2Mn^(st) 2Mn^(nd) or 140 or 130or 124 2Ni^(nd) 6Ni^(st) 1Mn^(nd) 194 2Mn^(st) 1Ni^(nd) 4Ni^(st) 204 or190 2Mn^(nd) or 2Ni^(nd) 6Ni^(st) 230 1Ni^(nd) 1Mn^(st)2Ni^(st) or 232or 244 or 220 2Mn^(st)or 2Ni^(nd) 1Mn^(nd) 330 2Mn^(st) 1Ni^(nd)1Mn^(nd) 324 523 2Mn^(st) 2Ni^(nd) 524 688 4Mn^(st) 2Ni^(st) 1Mn^(nd)678 2Ni^(nd)

FIG. 3 shows a graph illustrating data based on first principlecalculations of relative energy of different cathode compositions as afunction of the number of atomic pairs (M4M5) within the lithium cobaltoxide structure. Atomic pairs include Mn—Ni pairs and Ni—Ti pairs. Therelative energy is calculated with respect to lowest energyconfiguration of each composition. For example, Mn—Ni pair calculationsused 4 atomic % Mn—Ni pairs, and Ni—Ti pair calculations used 4 atomic %Ni—Ti pairs. This graph indicates a clear association of higher atomicpairs and higher relative energy.

FIGS. 4 and 5 show scanning electron microscope (SEM) images of an NM77composition at higher and lower magnifications, respectively. FIG. 5Ashows a single particle of a NM77 composition and FIG. 5B shows multipleparticles of a NM77 composition.

FIG. 6 shows magnetic angle spinning (MAS) NMR spectra for NM1616samples. The chemical shifts related to both Ni and Mn ions. Inparticular, labeled peaks within the MAS NMR spectra correspond to Ni—Mnshort range order interaction within the lithium cobalt oxide structure.These labeled peaks can be taken as finger prints that Ni and Mn ionsexist at adjacent Li+ ions.

Table 3 below summarizes some properties of an NM77 composition,specifically, Li_(1.004)Co_(0.86)(Ni_(0.07)Mn_(0.07))O₂, as well ascharacteristics of a lithium-ion cell having a positive electrode withthe NM77 composition.

TABLE 3 Property MN44 MN77 MN1616 Average working voltage 3.98 4.09 3.93at 0.2 C discharge rate 4.6-2.75 V (V) Specific 1^(st) discharge 210 204200 capacity at 0.2 C, 4.6-2.75 V cutoff (mAh/g) 1^(st) cycle 92 96 92efficiency, % Lattice parameter based a = 2.8209, a = 2.8223, a = 2.838,on R-3m space group c = 14.0836 c = 14.1140 c = 14.162 (Å)

As indicated above in Table 3, the NM77 composition has R-3m latticestructure characterized as having lattice parameters a=2.82231 Å andc=14.11403 Å, and the NM1616 composition has R-3m lattice structurecharacterized as having lattice parameters a=2.838 Å and c=14.162Å—which are generally larger than a and c values for a LiCoO₂ structurewithout Ni—Mn pairs (e.g., a commercial LiCoO₂ has a=˜2.815 Å, c=˜14.07Å). In general, the compositions having Ni—Mn pairs provide refinedlattice parameters of a≥2.817 Å and c>14.070 Å. It is believed thislarger dimensioned R-3m lattice structure provides larger spacingbetween layers of each of the NM77 and NM1616 compositions, therebyproviding improved intercalation of lithium ions between the layers asthe battery cell is charged and discharged. As described above, theNi—Mn pairs generally provide a more stable R-3m lattice structurecompared to a LiCoO₂ structure without Ni—Mn pairs. It is believed thatthis more stable lattice structure is less vulnerable to collapse orsliding as lithium ions are removed and replaced, thereby providing amore reliable lattice structure for the lithium ions to move into andout of. That is, the Ni—Mn pairs result in a cathode that is capable ofenduring more charge and discharge cycles without lattice structurebreakdown compared to a LiCoO₂ structure without Ni—Mn pairs. The sameis true for metal pairs, as described herein.

Table 3 also indicates that a battery cell having the NM77 compositionis characterized as operating with a specific first discharge capacityis significantly higher than that of a LiCoO₂ battery without Ni—Mnpairs. Specifically, a NM77 composition battery cell can operate at aspecific first discharge capacity of about 215 mAh/g compared to about170 mAh/g for a LiCoO₂ battery without Ni—Mn pairs.

FIG. 7 shows a differential capacity analysis (dQ/dV) plot for a batterycell having an NM77 electrode composition. In general, a dQ/dV plot isused to indicate the tendency of a battery cell to degrade over a numberof charge and discharge cycles. Voltage (V) and charge (Q) data arecollected as the cells are charged and discharged a designated number ofcycles. These data are then differentiated to create differentialcapacity, dQ/dV (V, n), versus V for the nth measured cycle. FIG. 7shows a dQ/dV plot for 5, 10 and 15 cycles. The top curves (having dQ/dVabove zero) correspond to charge cycles and the bottom curves (havingdQ/dV below zero) correspond to discharge cycles.

FIG. 7 shows that the dQ/dV curves for 5, 10 and 15 cycles have verysimilar shapes and closely overlap with each other. This indicates thatthe performance of the battery cell with the NM77 electrode compositionis stable over these charge/discharge cycles, indicating a very stablecrystal lattice structure over numerous cycles of lithium ion transport.In contrast, of dQ/dV curves of standard battery cells with commerciallyavailable LiCoO₂ electrode compositions will show degradation afterabout 10 cycles—i.e., the peaks of the curves will lessen or evendisappear at around 10 cycles.

The peaks of the dQ/dV curves correspond to voltage potentials at whichmaximum lithium ion transport occurs, and at which maximum electron flowoccurs. Standard battery cells with commercially available LiCoO₂electrode compositions typically have a maximum voltage potential ofabout 3.7 V. FIG. 7 indicates that the battery cell with the NM77electrode composition maximum reside around 3.9 V. These resultsindicate that, in addition to degrading less than standard LiCoO₂electrodes, NM77 electrodes also provides a marked increase in batteryenergy (corresponding to a higher energy capacity) compared to standardLiCoO₂ electrodes. In some embodiments, a lithium-ion battery having acathode with a composition in accordance with Formula (I) or 2 willprovide a maximum voltage potential of at least 3.9 V.

Table 4 below summarizes some performance characteristics of samplebattery cells (1-8) having positive electrodes of differentcompositions, including different NM77 compositions, a standard LiCoO₂composition without nickel or manganese (referred as “LCO”), and aLi_(1.02)Co_(0.95)Mn₀₀₄O₂ (referred as “LCMnO”).

TABLE 4 Sample No. 1 2 3 4 5 6 7 8 cathode composition NM77 NM77 NM77NM77 NM77 NM77 LCO LCMnO Li/M Li_(0.969) Li_(0.989) Li_(1.004) Li_(1.02)Li_(1.03) Li_(1.04) — — (M = Co_(0.93) Mn_(0.07)) 1^(st) cycle charge220 mAh/g 223 mAh/g 229 mAh/g 227 mAh/g 228 mAh/g 224 mAh/g 238 mAh/g229 mAh/g capacity 1^(st) cycle discharge 206 mAh/g 209 mAh/g 215 mAh/g212 mAh/g 214 mAh/g 210 mAh/g 232 mAh/g 214 mAh/g capacity 1^(st) cycleefficiency 94% 94% 94% 93% 94% 94% 98% 94% 1^(st) cycle average 4.09V     4.08 V     4.09 V     4.08 V     4.07 V     4.07 V     4.07 V    4.10 V     discharge V 52^(nd) cycle discharge 191 193 198 196 197 196181 167 capacity 52^(nd) cycle discharge V 4.06 4.04 4.07 4.05 4.05 4.053.85 4.06 Capacity retention % 93 93 92 93 92 93 78 78 (52^(nd)/1^(st)cycle) Energy retention % 92 92 91 92 92 93 74 77 (52^(nd)/1^(st) cycle)1^(st) cycle energy 3362 3410 3523 3451 3484 3412 3779 3515

Table 4 shows data for 1^(st) cycle charge and discharge capacities(mAh/g) for the cells at 0.1° C. between 4.6V and 2.75V, 1^(st) cycleefficiency (%), 1^(st) cycle average discharge voltage (V), 52^(nd)cycle average discharge capacity (mAh/g) for the cells at 0.1° C.between 4.6V and 2.75V, and 52^(nd) cycle average discharge voltage(V)—each averaged over three cells. Table 4 also shows data for capacityretention % and energy retention % of 52^(nd) cycle versus 1^(st) cycle.

Table 4 indicates that the cells having NM77 electrode compositions showless performance degradation over charge/discharge cycles compared tothe cells having LCO and LCMnO electrode compositions. In particular,the capacity retention and energy retention percentages of 52^(nd)cycles versus 1^(st) cycles are much higher for the cells having NM77electrode compositions (i.e., 93% and 92%) compared to the cells havingLCO and LCMnO electrode compositions (i.e., 78%, 74% and 77%). Thesedata further support the above-described improved stability provided bythe Ni—Mn pairs with the NM77 electrode compositions. In someembodiments, a lithium-ion battery having a cathode with a compositionin accordance with Formula (I) or 2 will provide a charge capacityretention (52^(nd)/1^(st) cycle) of at least 92%.

FIG. 8 shows Raman spectra of layered compositions of LiCoO₂ (referenceLCO), LiCoO₂ composition with 7 atomic % manganese and no nickel, andNi—Mn substituted LiCoO₂ of different amounts of Ni—Mn (specifically,NM44, NM77, NM1010 and NM1616). According to the factor-group analysis,the layered LiCoO₂ with R-3m structure is predicted to show twoRaman-active A_(1g) and E_(g) modes, which are observed at around 596cm⁻¹ and around 486 cm⁻¹, respectively. With the addition of Mn or Ni—Mninto the structure, a peak at around 320 cm⁻¹ is observed, whichincreases intensity with increasing amounts of Ni—Mn pairs. In addition,increasing amounts of Ni—Mn pairs result in a peak around 450 cm⁻¹.Furthermore, Ni—Mn pairs are associated with peaks at frequencies abovethe 596 cm⁻¹ band and below the 486 cm⁻¹ band due to the Mn—O and Ni—Ovibrations. The intensity of the scattering above 596 cm⁻¹ band seems toincrease with increasing Mn substitution, and decreasing with increasingNi substitution. In addition, increasing Ni substitution slightlydecreasing the frequency of the Ni—Mn induced scattering below 486 cm⁻¹.

FIG. 9 shows a heat flow versus temperature graph comparing thermalstability of different cathode materials. The graph of FIG. 9 showsresults in accordance with differential scanning calorimetry (DSC)techniques for analyzing phase transitions of materials when heat isapplied. The graph shows heat flow curves for a NM77 composition (markedas LiCo_(0.86)(NiMn)_(0.07)O₂), a lithium cobalt oxide having 4 atomic %manganese (marked as LiCo_(0.96)Mn_(0.04)O₂), a lithium cobalt oxidehaving 7 atomic % manganese (marked as LiCo_(0.93)Mn_(0.07)O₂), and anundoped lithium cobalt oxide (marked as LiCoO₂). The cathode materialswhere harvested when being charged to 4.45V.

In general, peaks in a DSC curve correspond to exothermic or endothermicreactions, which are often accompanied with structural change of alithium cobalt oxide material. The onset temperature is defined as thelowest temperature at which the material initiates an exothermicreaction. The graph of FIG. 9 indicates that the undoped lithium cobaltoxide composition has a relative low onset temperature, i.e., around150° C. The graph indicates the NM77 composition has a higher onsettemperature, i.e., around 180° C. However, the lithium cobalt oxidecompositions having 4% and 7% manganese experienced structural changesat even higher temperatures, i.e., around 250° C. These results indicatethat lithium cobalt oxide compositions having 4% and 7% manganese havebetter thermal stability than the undoped lithium cobalt oxide materialand NM77 material.

FIG. 10 shows flowchart 1000 indicating a method of forming a batterycell with an electrode with a lithium cobalt oxide composition havingNi—Mn pairs, in accordance with some embodiments. At 1002, anickel-manganese-cobalt precursor is formed. At 1004, thenickel-manganese-cobalt precursor is combined with a lithium oxide(e.g., Li₂CO₃) in to form a solid-state lithium cobalt oxide compositionhaving Ni—Mn pairs. At 1006, the lithium cobalt oxide composition havingNi—Mn pairs is incorporated into an electrode for a battery cell.

In some embodiments, the lithium cobalt compositions in accordance withFormulae (I)-(IV) are in the form of a coating. FIGS. 11A-11D showcoated particles for cathode materials, in accordance with someembodiments. In these coated particle embodiments, a lithium cobaltoxide composition having heterogeneous atomic pairs are in the form of acoating around a core material of a different composition. In somecases, this configuration can improve the thermal stability of thecathode material.

FIG. 11A shows a lithium battery cathode particle 1100 that includescoating 1102, in accordance with some embodiments. Particle 1100represents one of a number of similar particles within a cathode for alithium ion battery cell. Particle 1100 is represented as having aspherical shape—however, particle 1100 can have any suitable shape,including a globular or other non-spherical shape. Particle 1100includes core 1101, which can be composed of any suitable cathodematerial, such as layered cathode, spinel cathode, olive cathode (e.g.,layered LiTMO₂, spinel LiM₂O₄, LiMPO₄, Li2MnO₃*LiTMO₂). In someembodiments, core 1101 is composed of a lithium cobalt oxide material.In some embodiments, core 1101 is composed of a lithium cobalt oxiderepresented by:Li_(a)Co_(b)M6_(c)O_(δ)  (Formula (V))where M6 is one or more of manganese (Mn), nickel (Ni), aluminum (Al),magnesium (Mg), titanium (Ti), zirconium (Zr), calcium (Ca), vanadium(V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), and ruthenium(Ru); and where 0.90≤a≤1.1, 0.5≤b≤1.0, 0<c≤0.5, 1.90≤δ≤2.10. In someinstances, M6 can be Mn, Ni, or the combination of Mn and Ni, along withAl as a dopant.

For example, core 1101 can be composed of lithium cobalt oxide dopedwith manganese. In some embodiments, core 1101 includes a lithium cobaltoxide doped with about 4 atomic % manganese or a lithium cobalt oxidedoped with about atomic 7 atomic % manganese. In some embodiments, core1101 is composed of a high voltage, high volumetric energy densitymaterial, such as described in U.S. Patent Publication No.2014/0272563A1, which is incorporated herein by reference in itsentirety.

Compositions in accordance with Formula (V) have high thermal stabilitywhen exposed to relatively high temperatures compared to other lithiumcobalt oxide compositions. Thus, a cathode composed of a lithium cobaltoxide material in accordance with Formula (V) will retain structuralintegrity at relatively high temperatures.

In some embodiments, the core is selected from a layered hexagonalrock-salt structure represented as LiTM₁-xMexM7O₂; where TM is Co, Mn orNi; Me is Li, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru. In somecases, the core has a spinel cubic structure represented asLiMn₂-xMexO₄; where Me is Li, Ni, Co, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu,Zn or Ru. In some embodiments, the core has an olivine structurerepresented as LiTM₁-xMexPO₄; where TM is Co, Mn, Ni or Fe; Me is Li,Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru. In some embodiments, thecore is a layered-layered material such as represented byLi₂MO₃*LiTM1-xMexO₂; where M is Mn, Ru, Ti or Zr; TM is Co, Mn or Ni; Meis Li, Mg, Al, Ti, Zr, Ca, V, Cr, Fe, Cu, Zn or Ru.

Core 1101 is covered with coating 1102 (which can also be referred to asa shell), which can be composed of a lithium cobalt oxide composition inaccordance with one or more of Formulae (I), (II), (III), or (IV). Thatis, coating 1102 can be composed of a lithium cobalt oxide havingheterogeneous atomic pairs, such as Ni—Mn pairs. As described above,lithium cobalt oxide having heterogeneous atomic pairs generally have amore stable crystal structure than undoped lithium cobalt oxidecompositions and lithium cobalt oxide compositions having homogeneousatomic pairs (e.g., Ni—Ni or Mn—Mn pairs). In addition, lithium cobaltoxide compositions having heterogeneous atomic pairs are found to havehigher capacity and energy retention after cycle life testing.

One of the advantages of particle 1100 having coating 1102 of onecomposition and core 1101 of a different composition is that eachcomposition can provide different benefits. In particular, core 1101 canprovide high thermal stability to particle 1100 while coating 1102 canprovide relatively higher energy retention to particle 1100. Inaddition, some lithium cobalt oxide compositions having atomic pairs(i.e., in accordance with one or more of Formulae (I), (II), (III), or(IV)) can have a lower true density and lower average discharge voltagethan a lithium cobalt oxide composition without atomic pairs (e.g., inaccordance with Formula (V)). That is, core 1101 can allow for denserpacking of a lithium cobalt oxide composition (i.e., provide a highervolumetric energy density for the battery cell). Thus, core 1101 canprovide high energy density and high thermal stability, and coating 1102can provide high energy retention.

The relative volumes of core 1101 and coating 1102 can vary. In someembodiments, the relative volume of core 1101 is greater than that ofcoating 1102. In some cases, the thickness of coating 1102 ranges fromabout a couple of (i.e., two) nanometers to about five micrometers, andthe diameter of particle 1100 ranges from about couple of (i.e., two)micrometers to about thirty micrometers.

FIG. 11B shows a lithium battery cathode particle 1104, in accordancewith other embodiments. Particle 1104 includes coating 1102, which canbe composed of a lithium cobalt oxide in accordance with one or more ofFormulae (I), (II), (III), or (IV). In addition, second coating 1106covers coating 1102. Thus, in the embodiment show in FIG. 11B, coating1102 can be referred to as a first coating.

Second coating 1106 can be composed of a dielectric material, such asone or more of aluminum oxide (Al₂O₃), aluminum fluoride (AlF₃),aluminum phosphate (AlPO₄), zirconium oxide (ZrO₂), titanium oxide(TiO₂), magnesium oxide (MgO) etc. In some embodiments, second coating1106 has a porous structure such that portions of first coating 1102 areuncovered and exposed, thereby providing access to the lithium cobaltoxide composition of first coating 1102. In this way, lithium ions canpass through second coating 1106 during charge and discharge cycles. Oneof the functions of second coating 1106 can be to prevent or reduceexposure of second coating 1106 (and sometimes core 1101) to hydrogenfluoride (HF), which can exist within the battery electrolyte. It isbelieve the HF can degrade a lithium oxide-based material. Therefore, byreducing exposure of first coating 1102 to HF can reduce degradation offirst coating 1102 (and sometimes core 1101), thereby slowing down theimpedance growth as a result of degraded surface of particle 1100 anddecreasing the electrical resistance of the battery cell. In this way,second coating 1106 can stabilize the surface of particle 1100 withrespect to the electrolyte composition.

The thickness of second coating 1106 can vary depending on a number offactors. In some embodiments, the thickness of second coating 1106ranges from less than about one nanometer to about a couple of (i.e.,two) micrometers. In some cases, the thickness of coating 1102 rangesfrom about a couple of (i.e., two) to about five micrometers, and thediameter of particle 1104 ranges from about a couple of (i.e., two)micrometers to about thirty micrometers.

FIG. 11C shows a lithium battery cathode particle 1108, in accordancewith other embodiments. Particle 1108 includes core 1101, which iscovered with coating 1102 (also referred to as a first coating or alithium cobalt oxide coating doped with atomic pairs) composed of alithium cobalt oxide in accordance with one or more of Formulae (I),(II), (III), or (IV), as well as second coating 1106 composed of adielectric material. In contrast to particle 1104 of FIG. 11B, secondcoating 1106 is positioned between core 1101 and first coating 1102. Insome cases, this arrangement with coating 1102 being the outermost layerof particle 1108 provides a cathode material having good thermalstability and energy retention. In some embodiments, the thickness ofsecond coating 1106 ranges from less than about one nanometer to about acouple of (i.e., two) micrometers. In some cases, the thickness ofcoating 1102 ranges from about couple of nanometers to about fivemicrometers, and the diameter of particle 1104 ranges from about coupleof (i.e., two) micrometers to about thirty micrometers.

FIG. 11D shows a lithium battery cathode particle 1110, in accordancewith other embodiments. Particle 1110 includes core 1101, which iscovered with coating 1102 composed of a lithium cobalt oxide compositionin accordance with one or more of Formulae (I), (II), (III), or (IV).Particle 1110 also includes second coating 1106 and third coating 1112,which are each composed of dielectric material. In some cases, thisarrangement with particle 1108 having layers of dielectric coatings andbetween layers of lithium cobalt oxide material provides a cathodematerial having good thermal stability and energy retention.

It should be noted that the particles presented in FIGS. 11A-11D canhave any suitable shape, including spherical, globular or othernon-spherical shape. The size of the particles presented in FIGS.11A-11D can vary depending on a number of factors. In some embodiments,the particles in FIGS. 11A-11D have a diameter ranging from about coupleof (i.e., two) micrometers to about thirty micrometers.

It should also be noted that the embodiments described above withreference to FIGS. 11A-11D are presented as examples and that anysuitable combination and number of coatings can be used in order tocreate a cathode material having a prescribed performance, such asenergy density, thermal stability, discharge capacity, dQ/dV values,etc. That is, the particles can be composed of one or more lithiumcobalt oxide coatings doped with atomic pairs and/or one or moredielectric coatings, arranging in any suitable order. Put another way,the particles can include multiple first coatings and/or multiple secondcoatings.

Methods of forming coated particles, such as particle 1100, 1104, 1108and 1110, can include any of a number of suitable coating techniques.One technique involves forming a solution of a nickel-manganese-cobaltprecursor using the techniques described above. Then, particles formedof a core material are immersed in the solution such that the corematerial becomes coated with the nickel-manganese-cobalt material.Another technique involves forming nanoparticles of thenickel-manganese-cobalt precursor. The nanoparticles are then applied tosurfaces of particles formed of the core material. The nanoparticles canbe applied using dry or wet blending techniques. In some cases, acalcination or melting process following the blending process is appliedto stabilize the nanoparticles to surfaces of the particles composed ofthe core material.

FIGS. 12A and 12B show SEM images of uncoated and coated particles. FIG.12A shows particles composed of a lithium cobalt manganese oxidecomposition, and FIG. 12B shows particles composed of a lithium cobaltmanganese oxide composition core having a coating composed of acomposition having Ni—Mn pairs. As shown, the coated particles (FIG.12B) appear to have different surface textures compared to the uncoatedparticles (FIG. 12A).

FIG. 13 shows Raman spectra of particles having different compositions,some coated and some not coated. Compositions include an uncoated 4atomic % manganese LiCoO₂ composition (4% Mn), a 4 atomic % manganeseLiCoO₂ core covered with a 3 atomic % NiMn LiCoO₂ composition (3% NMcoated), a 4 atomic % manganese LiCoO₂ core covered with a 4 atomic %NiMn LiCoO₂ composition (4% NM coated), a 4 atomic % manganese LiCoO₂core covered with a 5 atomic % NiMn LiCoO₂ composition (5% NM coated),and an uncoated 16 atomic % NiMn LiCoO₂ composition (NM1616).

The Raman spectra of FIG. 13 indicate that after coating withcompositions having Ni—Mn pairs, the shoulder peak at around 650 cm⁻¹ ismore pronounced compared to the uncoated 4% Mn composition. Furthermore,the shoulder peak at around 650 cm⁻¹ is even more pronounced in theuncoated NM1616 composition. This indicates that samples having coatingswith compositions having Ni—Mn pairs are more stable than to theuncoated 4% Mn composition, but that uncoated NM1616 compositionprovides even better stability. It should be noted, however, that thecoating configuration could provide a more surface stable high-energycathode. Thus, these factors should be considered and balanced whendesigning a battery cell for a particular application.

FIG. 14 shows a graph illustrating energy retention of battery cellshaving LiCoO₂ (standard, commercially available), NM44, NM77, NM1010,and NM1616 cathode compositions. In each graph, the energy retentionvalues (y-axis) are normalized with respect to a first cycle. The graphof FIG. 14 indicates that battery cells having higher amounts of Ni—Mnpairs have higher energy retention over 50 cycle counts.

FIG. 15 shows a graph illustrating energy retention of battery cellshaving particles of different coating compositions after a number ofcharge and discharge cycles. Performance of a battery cell withparticles having LiCo_(0.96)Mn_(0.04)O₂ core with an Al₂O₃ coatingcompared to a battery cell with particles having LiCo_(0.96)Mn_(0.04)O₂core with a Ni—Mn and an Al₂O₃ coating. The energy retention (y-axis) isnormalized with respect to the first cycle. The graph of FIG. 15indicates that the battery cell with particles having a Ni—Mn and Al₂O₃coating has higher energy retention over 28 cycle counts.

FIG. 16 shows a graph illustrating energy retention (%) of half cellshaving particles of different coating compositions after a number ofcharge and discharge cycles. The half cells are coin cell cycled at C/52.75-4.5V at 25 degrees C. Performance of a half cell with particleshaving Al₂O₃ coating is compared to a battery half cell with particleshaving a Ni—Mn and Al₂O₃ coating. The graph of FIG. 16 indicates thatthe half cell with particles having a Ni—Mn and Al₂O₃ coating has higherenergy retention over about 46 cycle counts.

FIGS. 17A-17E show capacity analysis (dQ/dV) plots for battery cellshaving LiCoO₂ (standard, commercially available), NM44, NM77, NM1010,and NM1616 cathode compositions, respectively. Each dQ/dV plot is basedon performance of a coin half cell at C/5 charge/discharge rate2.75-4.6V. The solid lines in the plots are dQ/dV curves of a 1^(st)cycle after formation cycle, and the dotted lines are dQ/dV curves every5 cycles thereafter. FIGS. 17A-17E indicate that the performance of thebattery cell with the NM44, NM77, NM1010, and NM1616 cathodecompositions are stable over numerous charge/discharge cycles comparedto the standard battery cells with commercially available LiCoO₂composition.

The battery cells described herein can be used in any suitableelectronic device, such as device 1800 of FIG. 18. In some cases,electronic device 1800 is a consumer electronic device, such as aportable computing device (e.g., mobile phone, tablet device, wearabledevice, laptop, media player, camera, etc.). Electronic device 1800includes interface 1802, which can include a user input component and auser output component. For example, interface 1802 can include visualdisplay, visual capture, audio output, audio input, button, keypad,touch screen, sensor and other components. Electronic device 1800 alsoincludes processor 1804, which can pertain to a microprocessor orcontroller for controlling operation of electronic device 1800.Electronic device 1800 further includes memory 1806, which can beaccessed by one or more components of electronic device 1800 and caninclude random-access memory (RAM) and read-only memory (ROM).Electronic device 1800 also includes battery 1808, which can providepower to various components of electronic device 1800. Battery 1808 cancorrespond to rechargeable lithium-ion battery that includes one or morebattery cells in accordance with embodiments described herein.

FIGS. 19A-19C show X-ray diffraction patterns of NM77, 4% Mn and LCO(standard LiCoO₂) compositions before and after 50 charge/dischargecycles. The compositions prior to charging/discharging are referred toas “pristine”. Each sample was cycled between 2.75 V and 4.6 V at C/5rate. FIG. 19A shows that the NM77 composition cathode had no structuralchanges, as indicated by not change in location or shape of X-raydiffraction peak between 18.8 and 18.9 two-theta degrees. This indicatesthat the crystal structure of the NM77 composition shows goodreversibility. In contrast, FIGS. 19B and 19C show the 4% Mn and LCOcompositions show significant shifting and changes in the shape at thepeak between 18.8 and 18.9 two-theta degrees after the 50charge/discharge cycles. That is, the crystal structures of the 4% Mnand LCO samples have irreversible change after cycle testing.

The battery cell performance of the different compositions will dependon the specific composition—e.g., extent of Ni—Mn pairing, amount of Me(if any)—as well as other factors. That is, any suitable atomicpercentages can be used in accordance with the Formulae (I)-(IV).

FIG. 20 shows a graph illustrating energy retention (%) of cells (singlelayer pouch cells) with different compositions at higher temperaturesafter a number of charge cycles. Each cell was cycled at 0.7 C charge, 1C discharge, with a reference point test (RPT) at C/5 charge/dischargeevery 25 cycles using 2.75-4.45V at 45 degrees C. As shown, the cellhaving the LiCo_(0.86)(NiMn)_(0.07)O₂ composition has a much higherenergy retention at higher temperatures compared to the cell withoutNiMn pair composition.

Methods of forming the compositions in accordance with Formulae (I) and(II) can vary. Example 1 below presents a method of forming a NM77composition, specifically LiCo_(0.86)Ni_(0.07)Mn_(0.07)O₂, in accordancewith some embodiments.

Example 1

An aqueous solution of manganese, nickel and cobalt sulfate (Mn:Ni:Comole ratio 7:7:86) are dripped into a reactor having heated water.Ethylene Diamine Triacetic Acid (EDTA) is added and the pH is fixed at10.5 by adding a basic solution. After some time,nickel-manganese-cobalt precursor particles form (e.g., in salt formsuch as an oxide or a hydroxide), which are then washed, filtered anddried. The precursor particles are mixed with Li₂CO₃ in solid state byvarying the ratio of Li/metal to 0.96, 1.0 and 1.04. Following mixing,the mixed powder was heated then cooled. The sample was subsequentlyground, then sieved and re-fired at higher temperatures and allowed tocool. The final sintered black powder was sieved for use in anelectrochemical test as a cathode active material.

It should be noted that embodiments described herein are not limited tothe methods described in Example 1. For example, other methods offorming the precursor particles can be used. For instance, other methodsof mixing manganese, nickel and cobalt in solution state andprecipitating out homogenous combined particles may be used.Alternatively, manganese, nickel and cobalt can be combined in solidstate (e.g., in the form of manganese sulfate, nickel sulfate and cobaltsulfate). In other embodiments, a spray-dry process is used to form theprecursor particles.

Examples 2-5 below present methods of forming coated particlecompositions, in accordance with some embodiments.

Example 2: NM77 Coating on Li_(1.04)Co_(0.96)Mn_(0.04)O₂ Core

A predetermined amount of base powder (i.e.,Li_(1.04)Co_(0.96)Mn_(0.04)O₂) is weighed out in a container. An amountof cobalt and nickel, manganese and lithium precursor needed for adesired amount of LiCo_(0.86)Mn_(0.07)Ni_(0.07)O₂ coating (e.g., 1, 2and 3 wt. %) is calculated based on the weighed amount of base powder.The transition metal precursors include salts of cobalt, nickel andmanganese, such as nitrate, acetate, or other salts soluble in water oralcohol. The lithium precursor is in in the form of a carbonate,hydroxide, acetate, oxalate, nitrate or any suitable combinationthereof. The transition metal precursors and lithium precursor aredissolved in a small amount of water or alcohol to form a mixedsolution. The mixed solution is added drop-wise onto the base powderwhile stirring. The mixed solution added is such that the base powder isincipiently wet and well mixed (i.e., exhibits a damp consistency).After drying at 50-80° C., the dried base powder is heat-treated at 700°C. for 5 hours in stagnant air.

Example 3: NM1616 Coating on Li_(1.04)Co_(0.96)Mn_(0.04)O₂ Core

A predetermined amount of base powder (i.e.,Li_(1.04)Co_(0.96)Mn_(0.04)O₂) is weighed out in a container. An amountof cobalt and nickel, manganese and lithium precursor needed for adesired amount of LiCo_(0.68)Mn_(0.16)Ni_(0.16)O₂ coating (e.g., 1, 2and 3 wt. %) is calculated based on the weighed amount of base powder.The transition metal precursors include salts of cobalt, nickel andmanganese, such as nitrate, acetate, or other salt soluble in water oralcohol. The lithium precursor is in in the form of a carbonate,hydroxide, acetate, oxalate, nitrate or any suitable combinationthereof. The transition metal precursors and lithium precursor aredissolved in a small amount of water or alcohol to form a mixedsolution. The mixed solution is added drop-wise onto the base powderwhile stirring. The mixed solution is added such that the base powder isincipiently wet and well mixed (i.e., exhibits a damp consistency).After drying at 50-80° C., the dried base powder is heat-treated at 700°C. for 5 hours in stagnant air.

Example 4: NM1616 Coating on LiNi_(0.8)Co_(0.15)Al_(0.05)O₂ Core

A predetermined amount of base powder (i.e.,LiNi_(0.8)Co_(0.15)Al_(0.05)O₂) is weighed out in a container. An amountof cobalt and nickel, manganese and lithium precursor needed for adesired amount of LiCo_(0.68)Mn_(0.16)Ni_(0.16)O₂ coating (e.g., 1, 2and 3 wt. %) is calculated based on the weighed amount of base powder.The transition metal precursors include salts of cobalt, nickel andmanganese, such as nitrate, acetate, or other salt soluble in water oralcohol. The lithium precursor is in in the form of a carbonate,hydroxide, acetate, oxalate, nitrate or any suitable combinationthereof. The transition metal precursors and lithium precursor aredissolved in a small amount of water or alcohol to form a mixedsolution. The mixed solution is added drop-wise onto the base powderwhile stirring. The mixed solution is added such that the base powder isincipiently wet and well mixed (i.e., exhibits a damp consistency).After drying at 50-80° C., the dried base powder is heat-treated at 500°C. for 5 hours in stagnant air.

Example 5: NM1616 Coating on LiNi_(0.82)Co_(0.13)Mn_(0.055)O₂ Core

A predetermined amount of base powder (i.e.,LiNi_(0.8)Co_(0.15)Al_(0.05)O₂) is weighed out in a container. An amountof cobalt and nickel, manganese and lithium precursor needed for adesired amount of LiCo_(0.68)Mn_(0.16)Ni_(0.16)O₂ coating (e.g., 1, 2and 3 wt. %) is calculated based on the weighed amount of base powder.The transition metal precursors include salts of cobalt, nickel andmanganese, such as nitrate, acetate, or other salt soluble in water oralcohol. The lithium precursor is in in the form of a carbonate,hydroxide, acetate, oxalate, nitrate or any suitable combinationthereof. The transition metal precursors and lithium precursor aredissolved in a small amount of water or alcohol to form a mixedsolution. The mixed solution is added drop-wise onto the base powderwhile stirring. The mixed solution is added such that the base powder isincipiently wet and well mixed (i.e., exhibits a damp consistency).After drying at 50-80° C., the dried base powder is heat-treated at 500°C. for 5 hours in stagnant air.

In some embodiments described below, various methods of synthesizinghydroxide precursors are disclosed in Examples 6-11.

Example 6

Hydroxide precursors with the desired transition metal combination, forexample: Co_(0.97)Mn_(0.03)(OH)₂ were synthesized via a coprecipitationprocess. During the process, a metal sulfate solution of the targetedcomposition and a NaOH solution were independently pumped into a 4 Lcontinuous stirred tank reactor (CSTR) with the pH and temperature wellcontrolled. At the same time, complexing agents (NH₄OH or EDTA) wereintroduced into the tank to control the growth and density of thehydroxide particles. Additionally, a cover gas of N₂ is bubbled into thereactor to prevent the oxidation of the transition metals. After aninitial growth time, the particles in the reactor begin to round anddensify. The precursor is collected from the process as dense sphericalparticles, having tap densities as high as 2.00 g/cc. The powder cake iswashed, filtered, and dried. The resulting precursor particles arecomposed of plate-like primary grains (FIG. 21). The primary grains aredensely woven into spherical secondary particles with the D50 rangingbetween 15-25 um. This powder is used as a precursor that is laterblended with other particles, such as lithium salts, and other precursorpowders to be reacted together in a high-temperature process to producea lithiated-oxide material with the desired properties for a high-energydensity Li-ion cathodes. The spherical shape and the wide particledistribution of these particles allow them to be packed with the highestpacking efficiency, which is critical for the high electrode density.

Example 7

A coprecipitation process as described in Example 1 is started. Thecomposition of the present material is chosen for its high energyretention, although its energy density may be considered substandard. Inthis example, the particles are immediately harvested from the reactorand washed. At this early stage of coprecipitation, the particles areirregular-shaped and have an open cancellous structure. The precursorparticles are milled in water to produce sub-micron particles, which aresubsequently filtered and dried (FIG. 22). This precursor (FIG. 22) isdry-blended with the appropriate amount of Li-salt and the baseparticles prepared in Example 1. The mixture is calcined in air at atemperature, for example 1085° C., and process time, for example 15 h,such that the particles interact and form a particulate material withthe physical, chemical and electrochemical properties described as theinventive material (FIG. 23).

Example 8

The coprecipitated precursors are produced as described in Examples 6and 7. The base material (Example 6) is blended with an appropriateamount of lithium salt and calcined at the required temperature and timeto produce particulates with a similar morphology to those shown in FIG.23. These particles are blended with the sub-micron hydroxide precursordescribed in Example 7 and with an appropriate amount of Li-salt. Themixture is heat treated at a temperature and time, for example from500-1050° C. for 5 h, to react the fine particles with the lithium saltand sinter the fine particles to and into the surface of thepre-calcined base particles (FIG. 24). The sintering temperature andtime are chosen to control the extent of diffusion of the fine particlesinto the surface of the base material.

Example 9

An alternative approach is to pre-lithiate and calcine the base and fineparticles separately at a lower temperature 500-900° C. before blending,and then heat-treating the fine particles with the base material athigher temperatures (900-1100° C.) to bond them together and allowinterdiffusion of elements. Other blending and calcination approachescan be conceived to achieve the same results as described here.

Example 10

An alternative approach is to coprecipitate, lithiate, and calcine thebase particles as in Example 8. Then a solution of acetates and/ornitrates containing LiCo(MnxNiyAlz)O was prepared and mixed with thebase particles to form an incipient wet mixture. The mixture was driedand then calcined between 600-900° C. FIG. 25 is a flow chart of thevarious compositions and process parameters.

Example 11

An alternative approach to produce the precursor of the inventivematerial is to carry out the coprecipitation process for the baseparticles as described in Example 6. Then, as the particles have grownand densified to their near-optimum properties, the process is containedas a batch process, and the metal-ion feedstock solution is changed toproduce the energy-retentive composition defined in equation:Li_(α)Co_(1-x-y-z)(Mn_(x)Ni_(y)Al_(z))O_(σ), wherein 0<y≤x≤0.2,0.98≤α≤1.02, 1.99≤δ≤2.01. The coprecipitation process then continuesuntil the hydroxide precursor particles have been overlaid with thedesired fraction of the new composition. These precursor particles arewashed, dried and calcined with lithium salts as described earlier toproduce a finished cathode powder.

Example 12: NM1616 Coating on LiNi_(0.8)Co_(0.15)Al_(0.05)O₂ Core

Coin cells were made from the electrode material described in Example 7,using a Li disk anode (½ cell) to demonstrate the effects of theinventive modification. Three cells are compared in FIG. 6 for theirdischarge capacity. The 3% Mn baseline has a composition: (as determinedby high precision ICP-OES); the 2 wt % NM1616 (referring to a lithiated2 wt % overlay containing a nominal 16 mol % Mn, 16 mol % Ni, andbalance Co, or resulting in an overall composition of the base and theoverlay: and the 5 wt % NM1616 (referring to a lithiated 5 wt % overlaycontaining a nominal 16 mol % Mn, 16 mol % Ni, and balance Co, orresults in an overall composition of the base and the overlay. All ofthe materials are coated with 0.05 wt % Al₂O₃ using a wet impregnationprocess of Al-nitrate salts, dried and calcined at 500° C. in air. The3% Mn baseline starts out with a discharge capacity of 184 mAh/g, whilethe 2 wt % NM1616 overlaid material has a lower capacity of 182 mAh/g,however, the overlaid material shows better capacity retention over 25cycles. The 5 wt % NM1616 has a lower capacity of 179 mAh/g, yet alsoshows better capacity retention than the baseline.

It is determined that during processing, the overlaid materials maintaina certain amount of separation of the overlay from the base material;i.e., the elements of the overlay have not completely distributed intothe base, but have a surface that is enriched with the initialcomposition of the overlay material.

Further evidence of improved energy retention is shown in FIG. 27. Thenormalized energy retention is improved by overlaying increasing amountsof NM1616 on the 3% Mn baseline material. This improvement is also seenin the average discharge voltage (FIG. 28). The best voltage retentionis seen for the 5 wt % NM1616 overlaid material.

The benefits gained from an increased amount of overlay on the basematerial are offset by a reduction in capacity with increased NM1616 asshown in FIG. 26. Considering the capacity and voltage retention, thebest overlay composition is between 2 and 5 wt % NM1616.

The NM1616 composition was chosen for its excellent energy retention,however, there are other compositions of Mn and Ni substituted LiCoO2that may also provide good energy retention while maintaining highenergy density. Additionally, 3% Mn was chosen as the base compositionbecause of its high energy density and retention. Other compositionsincluding variable Al and Mn additions can further improve energydensity and retention.

Example 13

The assumption that the NM1616 overlay does remain near the surface ofthe particle after high temperature processing is substantiated by Ramanmicrospectroscopy. This surface-sensitive technique shows the effect ofLi, Mn and Ni additions. In FIG. 29, a comparison is made betweenbaseline 4% Mn (M4) with 2 wt % and 5 wt % NM1616 overlays and pureNM1616 powder. The Raman spectrum for NM1616 shows an upward shift inthe major peak compared to M4 and 2 wt % and 5 wt % NM1616; and the‘knee’ between 620-680 cm-1 has greater intensity and has narrowed forNM1616. The 2 wt % and 5 wt % MN overlays show spectra that lie inbetween the M4 and NM1616. The knee size and shape is determined by theamount of Ni, Mn, and Li content in the compound. As such, this figureillustrates that the surfaces of both 2 wt % and 5 wt % show similarsurface behavior to pure NM1616.

Example 14

The thermal stability of a baseline material containing 4% Mn isimproved with the addition of Mn to LiCo02. Stability is sacrificedslightly when 4% Mn is overlaid with NM1616. Differential scanningcalorimetry (DSC) is used to demonstrate thermal stability of lithiumion materials. Electrodes from each material were first cycled between2.75-4.6V vs. Li with 0.1 C and then charged to 4.6V and held at thisvoltage for 5 hours, before disassembling. The cycled electrodes wereharvested from the coin cells and then washed with Dimethyl carbonate(DMC) and dried in the glove box. The harvested electrodes were sealedin the stainless steel high pressure capsules with electrolyte [1.2 MLiPF6+EC:EMC (3:7 by weight)]. The sealed high pressure capsules wereheated from 30-400° C. with 10° C./min then cooled down to 30° C. FIG.10 shows DSC test results of LiCoO2, (4% Mn base), and (4% Mn overlaidwith NM1616). The onset temperature and the heat release for chargedLiCo02 are 190° C. and 0.54 J/g, respectively. While the onsettemperature for the charged (4% Mn base) has improved to 247° C. and theheat release has reduced to 0.28 J/g. The thermal stability of the (4%Mn overlaid with NM1616) is slightly less stable compared to the 4% Mnbase having an onset temperature of 240° C. and heat release of 0.37J/g; but maintains a better thermal stability than LiCo02.

During heating, the charged cathode goes through a phase transition thatreleases oxygen, which reacts exothermically with the electrolytesolvent resulting in a heat release. Manganese is considered to increasethermal stability. Addition of Mn stabilizes the structure of chargedand delays the structural change during heating. Co-addition of Ni willreduce the thermal stability of charged which is caused by the largestand fastest reduction of Ni4+ to Ni2+. (Seong-Min Bak, et al. ACS Appl.Mater. Interfaces 2014, 6, 22594-22601) However, well-balanced Co, Niand Mn ratios can also achieve good thermal stability.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not intended to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. A compound represented by Formula (II):Li_(a)Co_((1-2y))(M/M2)_(y)O_(δ)  Formula (II) wherein M1 is Ni; whereinM2 is Ti; wherein M1M2 represents metal pairs of M1 and M2; and wherein0<y≤0.4, 0.95≤α≤1.4, and 1.90≤δ≤2.10.
 2. The compound of claim 1,wherein 0<y≤0.25.
 3. The compound of claim 1, wherein 0.02≤y≤0.06. 4.The compound of claim 1, wherein 0.05≤y≤0.09.
 5. The compound of claim1, wherein 0.08≤y≤0.12.
 6. The compound of claim 1, wherein 0.14≤y≤0.18.7. The compound of claim 1, wherein 0.20≤y≤0.25.
 8. A cathode activematerial comprising the compound of claim
 1. 9. A cathode comprising acathode current collector and the cathode active material according toclaim 8 disposed over the cathode current collector.
 10. A battery cellcomprising: an anode comprising an anode current collector and an anodeactive material disposed over the anode current collector and thecathode of claim
 9. 11. A portable electronic device comprising: thebattery cell of claim 10.